Tuesday, October 27, 2009

bsg: the plan

Just got finished watching BSG: The Plan. Pretty good. Ties up some loose ends from the series, offers up the Tricia Helfer Variety Pack (my vote's for trashy brunette), and introduces a new minor character for one of the subplots. Lots of the show splices in footage from the series in with new scenes, so it's kind of a retrospective as well. The 2's (Simon) get a more prominent role, and Leeoben is still pretty freaky but a lot less spooky once his story is revealed.

Also, Dean Stockwell is either an exceptionally evil man or a bad ass actor, and that's all I'm going to say about that.

This is definitely worth checking out if you're a BSG freak like me.

amazon now offers cloud mysql

Just got some spam from Amazon announcing the availability of their RDS (relational database system). The idea is that they basically manage a mysql server for you, and data transfer between RDS and EC2 machines in the same zone is free.

Scratching out some rough numbers, that's about $85/mo for their low end db server.. backups included. They're also dropping the rate for linux EC2 instances, and that works out to about $63/mo.

Monday, October 26, 2009

plexiglass sucks

Spent the weekend cutting up a sheet of plexiglass for the table top. I hate cutting the stuff, but it seems to have worked out ok (aside from my complete inability to cut a straight line).

Ended up snagging a sheet of 36"x30" sheet of 0.203" acrylic from Home Depot for about $43 (total cost of project so far is around $120). Since 0.203" is about 5mm and the diameter of the laz0rs is 12mm, I decided to just cut 4 grooves at 45 degrees in each of the corners, then glue on a 1"x1" base plate on the bottom to support the lasers. I then cut about 8 3/4"x1/2" blocks to glue on the top side of the plexiglass on each side of the groove in order to something close to the top of the laser that I can bolt a cap on to.

The extra bits (baseplates and blocks) came from the scrap I had after cutting 3" off the sides and 5" off the top so that I ended up with a 33"x25" piece (32"x24" for projection area, 1" margin for mounting lasers and the frame later on). I also use a piece of scrap to do some test cuts and to check out the laser to make sure it was sitting about right down in the groove.

My previous experience was with much thinner plexiglass, and the only viable way to cut that was with a scoring tool. With this thicker stuff, so I was able to put masking tape on both sides of the sheet, draw the cut line, and move a jigsaw through it at about 1/2 speed without any melting or the sheet cracking. I did a test cut on some of the scrap I had left over without the tape and the blade made it about 2" into the cut before the melted plastic jammed the jigsaw blade.

And speaking of the blade... I went with a carbon blade designed for cutting metal.

For the 45 degree grooves, I cut in with the jigsaw, tried to round out a corner cut, and then just cleaned out any left over with a dremel.

Testing out with the laser showed revealed something I hadn't accounted for in my earlier designs -- the fact that lasers are very precise little bitches, and that while the grooves I made for them gets them pointing in generally the right direction there still needs to be some way to do fine grained calibration. Namely, elevate the rear end of the lasers and make sure that they're throwing the beam parallel to the glass.

Next tasks: rigging up power for all 4 lasers, doing tests to find out how far away to mount the camera, and figuring out how to mount the lasers so that they can be adjusted.

For the support frame, I'm kicking around just getting an old vanity cabinet or something to hold everything. Still ignoring the project problem for the time being.

Wednesday, October 21, 2009

math fail

So it turns out that if you want to like, play with electricity, you have to do some of that math crap. It also turns out that when you see numbers like "3.2V 25m" the "m" doesn't stand for milliamps, it means milliwatts... and using that math stuff, that works out like 7.8 mA.

P = V * C (power [watts] = voltage * current [amps])
V = I * R (voltage = current [amps] * resistance [ohms])

I was testing the lasers out by simply hooking the power leads up to my cell phone 5.5V cell phone battery, but later we rigged up something a little more stable with a 9V battery, and some alligator clips on a 270 ohm resistor. Turns out that's pushing 33 mA on 300 m.

Whups. It still worked, but apparently overclocking the lasers means you lose some of their life.

In other news, I snagged a Logitech Quickcam for Notebooks (yes, that whole thing is the product name... no version numbers or anything.. "for Notebooks) for around $40. The cam is way easy to disassemble as everything is screwed together, and driver support for Linux is in most current distros. IR filter popped out easily enough. For the regular light filter, I tried cutting out a square from an old floppy disk, but it severely dims the IR light at a distance of about 3 feet. Going to try an exposed negative next.

Still trying to figure out what I'm going to do about mounting the lasers on the acrylic. The diameter of the laser (including the casing) is about 1/2 an inch which is about 13mm, so just sitting the laser on top of the acrylic is going to be about 6mm above the surface (and it needs to be at one). Thinking about just getting the acrylic so that there's an extra inch on each side and cutting 4 1/4 inch wide slides at 45 degree angles in each corner. That should let me sit the laser so the beam is just right above the surface, make it easy to secure with some tape, and allow me to easily remove them from the board to make adjustments.

Now I just have to find a way to deal with the nightmare of cutting acrylic... :(

Tuesday, October 20, 2009

IR lasers finally arrive

So it only took 11 days, but the lasers are finally here. Was talking with TheDude about how I'm going to power them, and he suggested a USB hack and pointed me towards this maximumpc article that covers the basics. Have already checked them out to make sure that the light is visible on the webcam I'm thinking about snagging by simply hooking them up to the cellphone battery for a test run.

The numbers: I got 4 lasers, 3.2V each, 25 mA, currently unknown resistance. The plan is to appropriate the USB cable from a dead MS Intelliexplorer mouse and use that for USB power source. The USB port runs 5 volts at 100 mA in lower power mode, so I shouldn't need to worry about asking it for more power or anything.

The shopping info: I ordered 740 nm lasers with 89 degree line splitters from aizix.com for $11 each ($8 for laser, $3 for splitter attachements). Not entirely sure I would recommend them, but as of right now I don't know of anyone else who isn't selling just the diodes or the laser already as part of some other device.

ToDo list:

1) obtain the acrylic sheet and figure out how I'm going to mount these suckers (estimating $20 for the sheet)
2) acquire a camera (thinking about a $20 gigaware cam from The Shack) and modify it to remove the IR filter and possibly in a regular light filter by butchering a floppy disk
3) splice work for the lasers and make sure that the camera can see the touches
4) clean install of linux on an old PC and see if I can't get the nuigroup software up and running

Projector and the frame to hold all this remains question marks for the time being.

Friday, October 9, 2009

it's poetry in motion

So. I'm doing research on MT stuff this week. Got a friend who's pondering his own high altitude photography project based on the MIT stuff. The inventors of CCD are finally getting the credit they deserve. We're bombing the hell out of the moon. We've found out Europa's water is oxygen rich and Saturn has yet another ring. And we now know that T. Rex had feathers.

Yessir, I think we can safely break this video out for this week.

leaning towards laz0rs

After doing some more reading and watching the arbitraious's laser table demo, I'm pretty much sold on trying that out first. Aside from the fact that mounting 4 lasers sounds like a much easier task than 40 LEDs, it also sounds like the laser approach offers up better responsiveness. The lasers are slightly more expensive (around $8 per, whereas the LEDs are about $2.63 for 10 for the high end ones), but that's not really the major cost center of this project.

Plus, I'm sure that by simply ordering lasers online, your name automatically goes on some FBI watch list, so... +notoriety, amirite?

For the video camera, I'm planning on grabbing a $20 Gigaware 1.3MP cam from The Shack (looks like a flat disk... avoid the one that looks like a mini-quickcam-eyeball-with-a-bump-on-it) simply because it's so low profile.

The sticking point is what to use to actually project the image. I don't want to waste money on another projector, but TheDude pointed out that some of the pico pocket projectors are around $200 and designed explicitly for short throw distances. The other approach might be to just tear apart an LCD and get a fresnel lens. Still mulling that part over. It'll affect the height of the enclosure.

I'm also mulling over the construction of the frame to hold the acrylic sheet. Trying to decide if there's a way to have it hold the lasers in place without having to muck with the sheet itself, and looking for some IR absorbing material to line the insides with (for that token nod towards "safety"). Will probably start ordering parts tomorrow and see how it goes.

Thursday, October 8, 2009


Ok. Admission time. I don't know a damned thing about electronics, aside from the fact that capacitors are round and the big ones can probably kill you so just stay the hell away from them.

But it's become clear that some electrical work is going to need to get done in order to pull of the MT screen. The usual strategy of wait helplessly until New Egg sells isn't going to work this time.

So my new strategy was turning to Mr. I Grew Up MacGuyvering Radios Together with Bobby Pins and a Potato and Have an EE from the Air Force Academy -- aka, "Dad" for advice. But that went something like:

"Well, you'll need to get a couple of 82 ohm resistors."
"Wait. How'd you figure that out?"
*incredulous look* "You just take the voltage, add up the fronkus coefficient, and then subtract that from the average magnetosphere reading for the location where you'll be using the device."
"That doesn't sound right."
"And be sure you pick up a Henway with the breadboard at Radio Shack. You need a Henway, or this is going to blow up."
"What's a Henway?"
"Ohhhhh, about the same as rooster! HAHAHAHAH!"
".... You are so screwed when we start talking about whether or not to put you into a nursing home."
"Go do your own homework."
"Seriously. I'm going to watch 60 Minutes to make up the list."
"And get a haircut."

So I googled "electronic training that will really piss of my dad", and up came a link to:


Google for the acronym if that link is dead... there are lots of places that carry mirrors of it.

Navy Electrical and Electronics Training Series. It's basically about 20 "modules" that take you through simple DC stuff, converting mechanical energy to electrical, radio waves, logic gates, and wraps up with radar. It's targeted towards enlisted personnel, so it's written for someone with a high school level education and slants more toward the trade side of things than dipping too far down into the theory.

In short, if you've ever been curious about electronics but cringed in horror at the thought of going through a college level EE textbook, this is TFM you should R.

and now for a word from someone who's not so hot about steam

In plenty of previous posts, I've gushed about how Steam makes getting games painless and how cool the service is, but here's an article with the opposing viewpoint from some guy called Randy Pitchford.

His big thing seems to be that he simply doesn't trust Valve and that he thinks currently Steam is taking an unfair percentage of the game sale.

Which might be true.

But I tell you, I probably never would have bought CoD4 or Bioshock if they hadn't been on Steam and playable in a few hours. I know for a fact that I never would have jacked around with Titan Quest or the Oblivion games if they weren't on Steam and sold as cheap bundles as I wasn't about to drive out to Best Buy and go sifting through the bargain bins just to find copies of them.

I think the power of their distribution system is how easy it for games to keep selling beyond the initial launch window.

Wednesday, October 7, 2009

nuigroup and diy multitouch

Ho'k. It's no secret that I hate the mouse the way Skynet hates John Connor. If I could, I'd be sending California governors back in time to blow up Xerox PARC, but fscking physics just has to be a party pooper about that. The mouse is here to stay, and I'm just going to have to deal with it.

But there is one bright spark of hope for the human interaction with computers, and that is multi-touch. It's not revolutionary in the sense of dot-com Super Bowl commercials with some jackass in a black turtleneck staring off into distance at all the great things ordering printer paper online will let him accomplish kind of revolutionary, but more in the sense of "Hey, maybe if we like dig a shallow trench between these two towns and fill it with rocks and then some sand to smooth it out, the wagon trips won't be so bumpy" kind of revolutionary.

There are some amazingly cool things we can do from a user interface perspective beyond the simple pinch-to-zoom-in and ooh-look-I-just-threw-a-photo-across-the-desktop stuff we've seen so far. The folks over at NUI Group have a similar vision, and have started amassing information about what a MT interface should look like, how it should act, and all that good stuff.

And so, I started looking around for a multitouch screen I could buy so I could get in on the action.

The problem comes in with the fact that there's not really a whole lot of consumer stuff out yet. Windows 7 will include support for MT devices, and there's a few laptops that are beginning to show up on the radar, but stuff like MS's Surface display is in the $10K price range. If you're looking for something large but cost effective, the only solution appears to be building a FTIR device yourself.

I've started doing some research on how to put this all together, and it doesn't look too difficult. I'm planning on doing some research on the way and making notes somewhere to answer some of the questions I've had (ie, just how many IR LEDs do you need to get this working, can you sub in cheaper display technologies than an off the shelf projector, can I trick Krak into rubbing some peanut butter on his monitor, what sort of machine specs will be needed to run this smoothly, etc).

Until then, here's some links:

Maximum PC's DIY MT Table
Wired Article on Yotam Mann's DIY Laser based MT system
Gizmodo's coverage of Multipointer X
ENAC's MPX based project
arbatrarious's DIY Laser Table project (which I'm now leaning towards instead of FTIR)